08-09-2010, 06:58 PM
[quote name='adifrank' timestamp='1281365421' post='1610']
Hi. Thanks for all the information. I think I will order the Eg-S focus screen, since I figure I'll mostly be using MF. Only two questions:
1. How exactly does this screen improve manual focusing? Is there a particular technique used for this? From the images of the screen I've seen on the internet it doesn't look like there is a horizontal split image or something similar - it looks just blank.[/quote]
It works because it actually is what it says it is, a precision matte. In non-technical terms this means it is a very fine polished focusing screen, as compared to the rather coarsely polished standard focusing screen. Because it has such a fine structure, it represents DoF much, much more accurately than de standard focusing screen does, e.g., narrow DoF actually appears as narrow as it is, hence making MF much easier. The only disadvantage is that it is slightly less bright than a standard focusing screen, but to be very honest, not noticeably so.
This screen also allows you to MF anywhere on the screen, rather than only in the centre, like a screen with a split prismatic wedge in the centre, because it is the same precison matte all over. Furthermore, it doesn't become unusuable when stopping down or when the light levels get low: it just gets a little darker (ok, that's obviosu <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/biggrin.gif' class='bbc_emoticon' alt=':lol:' />), unlike a wedge which just goes half black, or completely black. Since the 5D II has such a bright VF, I find this little loss of brightness isn't a problem anyway. By the time I can't focus with it anymore with MF, I find the AF system has already thrown in the towel for some time already. I am talking light levels here like 1/15s with an F/5.6 lens and 3200 iso.
You don't see those on the standard focusing screen either. The lights are projected in, and the screen actually has some support built into it anyway, even if you don't see it. Some raised or lowered edges I'd think. This is why the focusing screens for the 1 Ds II, III and 1 D II and III are interchangeable: they have the same size screen and the AF points in the same position. The 1 D Mk IV has different ones and therefore requires different focusing screens. In short: you will see the red rectangular AF point highlights with this screen, just as before.
The only thing you shouldn't forget is to switch the support in Custom Functions IV to the correct screen, as metering is affected by the slightly darker Eg-S screen: the metering system is located in the prism housing, IOW, in the lightpath aftter the focusing screen, and hence gets a little less light too because of the slightly dimmer VF. The setting makes sure the metering systems takes this small loss into account. I reckon it is about 1/3 to 1/4 of a stop.
Kind regards, Wim
Hi. Thanks for all the information. I think I will order the Eg-S focus screen, since I figure I'll mostly be using MF. Only two questions:
1. How exactly does this screen improve manual focusing? Is there a particular technique used for this? From the images of the screen I've seen on the internet it doesn't look like there is a horizontal split image or something similar - it looks just blank.[/quote]
It works because it actually is what it says it is, a precision matte. In non-technical terms this means it is a very fine polished focusing screen, as compared to the rather coarsely polished standard focusing screen. Because it has such a fine structure, it represents DoF much, much more accurately than de standard focusing screen does, e.g., narrow DoF actually appears as narrow as it is, hence making MF much easier. The only disadvantage is that it is slightly less bright than a standard focusing screen, but to be very honest, not noticeably so.
This screen also allows you to MF anywhere on the screen, rather than only in the centre, like a screen with a split prismatic wedge in the centre, because it is the same precison matte all over. Furthermore, it doesn't become unusuable when stopping down or when the light levels get low: it just gets a little darker (ok, that's obviosu <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/biggrin.gif' class='bbc_emoticon' alt=':lol:' />), unlike a wedge which just goes half black, or completely black. Since the 5D II has such a bright VF, I find this little loss of brightness isn't a problem anyway. By the time I can't focus with it anymore with MF, I find the AF system has already thrown in the towel for some time already. I am talking light levels here like 1/15s with an F/5.6 lens and 3200 iso.
Quote:2. How does using the Eg-S with Canon 5D mark ii affect using auto-focus? As it seems there are no focus points marked on the screen - how does AF work?
Thanks.
You don't see those on the standard focusing screen either. The lights are projected in, and the screen actually has some support built into it anyway, even if you don't see it. Some raised or lowered edges I'd think. This is why the focusing screens for the 1 Ds II, III and 1 D II and III are interchangeable: they have the same size screen and the AF points in the same position. The 1 D Mk IV has different ones and therefore requires different focusing screens. In short: you will see the red rectangular AF point highlights with this screen, just as before.
The only thing you shouldn't forget is to switch the support in Custom Functions IV to the correct screen, as metering is affected by the slightly darker Eg-S screen: the metering system is located in the prism housing, IOW, in the lightpath aftter the focusing screen, and hence gets a little less light too because of the slightly dimmer VF. The setting makes sure the metering systems takes this small loss into account. I reckon it is about 1/3 to 1/4 of a stop.
Kind regards, Wim
Gear: Canon EOS R with 3 primes and 2 zooms, 4 EF-R adapters, Canon EOS 5 (analog), 9 Canon EF primes, a lone Canon EF zoom, 2 extenders, 2 converters, tubes; Olympus OM-D 1 Mk II & Pen F with 12 primes, 6 zooms, and 3 Metabones EF-MFT adapters ....